1. Field of the Invention
The present invention relates to a zoom lens camera having a power zoom function.
2. Description of the Related Art
Electronic still cameras (i.e., still video camera), have appeared in recent years, the image of one frame (one or two fields) being recorded on one track of a magnetic disk. Accordingly, the magnetic disk is controlled so that it makes one revolution at the period of one field (1/60 sec. according to NTSC).
Since the magnetic disk, which serves as a recording medium, is rotated at such a high speed, a large number of frames can be shot in quick succession (i.e., continuous shooting mode), such as 1, 2 or 5 frames per second, for a desired period of time.
By combining this continuous shooting mode with zooming, a series of images which are gradually enlarged or reduced can be photographed.
In addition, it is possible to check a change in the image before it is actually photographed, by setting a monitor mode in which the image that is read out from an imaging device is displayed on a monitor.
It is noted that zooming causes the luminance to change in accordance with a change in the angle of view and therefore necessitates changing the aperture.
However conventional electronic still cameras suffer from the problem that when zooming is to be conducted, as described above, the aperture is controlled while the zoom lens is being moved, and consequently associated elements, i.e. the imaging circuit, recording circuit, aperture motor, tracking motor, spindle motor, etc. , are simultaneously activated, resulting in an increase in the peak current consumed.
Accordingly, the load on the power supply circuit increases and the rated capacity thereof must be increased, which results in an increase in the overall size of the camera and an increase in the manufacturing cost.